Method of making an electrical connection



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United States Patent METHOD OF MAKING AN ELECTRICAL CONNECTION Ward Cole, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application May 5, 1952, Serial No. 286,167

1 Claim. (Cl. 29-1555) This invention relates to improvements in the art of attaching terminals to a support and for forming electrical connections between a bared end of a cable and the terminal. a j,

In the past it has been a common practice to provide subassemblies which include headed terminal rivets with the shank portion of the rivet extending through opening in a support and then expanded over a bracket to secure it to the exterior of a support of a closure for a switch or other electrical devices. In the manufacture of such subassemblies, it requires the use of lock washers or clips and screws to attach bared areas of cur-. rent conducting wires to the bracket. This methodof attaching bared areas of. conducting wire tobrackets is obviously inefiicient and materially increases the labor cost in the production of the sub-assembly. Furthermore, this type of subassembly requires the stocking and use of a wide variety of conducting strips or brackets, lock washers, clips and screws best suited for attaching a wire to the bared areas of electric current conducting bracket. Also, this resulted in objectionable manufacturing complications in making a terminal subassembly for electric switches including a closure, terminals, rivets and lead wires of a particular size and kind.

An object of the present invention is to provide for overcoming the foregoing difliculties and other disadvantages of the prior sub-assemblies using terminal rivets for attaching brackets to a support to which wires are attached by screws.

Another object of the present invention is to provide an improved method of expediting attachments of one or more terminals to a support and for securing bared areas of insulated electric current conducting wires in a manner whereby perfect electrical connection is assured by fusion of metals.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

Fig. 1 is a view showing a fragment of a support in section, a terminal rivet in elevation, and a section of a closure after the terminal is inserted in the closure.

Fig. 2 is a sectional view showing a tool deforming the terminal rivet and showing the closure and terminal rivet in their respective conditions after the deforming operation.

Fig. 3 is a fragmentary sectional view of a closure and a terminal rivet after being deformed showing a bared conductor wire in position before the fusing operation.

Fig. 4 is a rear plan view of a switch closure show ing a plurality of terminal rivets attached thereto.

Fig. 5 is a view similar to Fig. 4, but showing conductor leads attached to the terminal rivets.

Fig. 6 is an enlarged fragmentary section of one of the terminal rivets after the welding operation.

, 2,782,491 Patented Feb. 26, 1957 Before explaining the present invention in detail, it is to be understood that the present invention is not limited to theparticular details of construction and arrangement of elements or parts shown in the accompanying drawing, since the invention is capable of other embodiments and of being carried out in various ways. Further it is to be understood that the phraseology or terminology set forth herein is for the purpose of description and not of limitation.

The illustrative embodiment of the invention shown in the drawings includes a support or closure 20 having a plurality of openings 21. In this instance the openings are counterbored to provide a shoulder 22, each opening receives a terminal rivet 23 of ductile material which is shaped as shown in Fig. 1. In this instance the rivet has a preformed head 25, a shank 26 and a reduced tapered portion 27 formed with a pocket or recess 28 therein. Each terminal rivet 23 is first inserted in a respective opening 21 and then the closure 20 with the required number of rivets 23 therein are positioned on a suitable support 30 with the head 25 located within the confines of the enlarged portion of the bore 21 and the shanks 26 and the reduced tapered portion 27 extending beyond the outer face 31 of the closure. The rivets are deformed by a suitable die or tool 32. This forming die or tool is formed and operable to deform the metal on a lip end of a head rivet to provide a groove with sharp edges to receive bared area of an insulated electric current conducting wire, and these sharp edges, as shown in Fig. 3, are adapted to be heated and fused with bared areas of conducting wire. In this instance the tool has a tapered recessed portion 33. The recess has a triangular rib 34, as shown in Fig. 2, which extends substantially diametrically across the bottom of the recess 33. The lower end of the tool is formed with a series of depending swaging lugs 35. The rivets 23 are secured to the closure 20 by the tool 32. When axial compressive force is applied to the rivet 23 by the tool 32 the swaging lugs 35 will engage the upper end of the shank 26 thereby causing portions of ductile metal of the shank to be cut from the sides of the shank and cold rolled over the cover or support, to form extensions 36 which overlie the outer face of the closure 20, see Fig. 2, to secure the rivet to the support or closure. As the extensions 36 are being formed the triangular rib 34 simultaneously forms transverse notches 37 on the end of the tip or tapered portions 27. The tool or forming die 32 which includes the recess 33 and the rib 34 produces a forming surface which is of the desired shape to reform the lip or end of the rivet and causes the ductile metal to be reshaped to produce arcuate-shaped sharp edges 38.

The next step is to place a bared area of an insulated cable 40 and then secure that bared area to the rivet. This is accomplished by positioning a bared end 42 into one of the notches and when the bared ends are so positioned they are fixed to the rivets by projection welding.

The welding circuit, not shown, suitable for welding the bared areas of the cables to respective rivets includes a welding transformer having a primary coil and a secondary coil whose leads are connected with welding electrodes. The electrodes are operable so that they will be forced axially against opposite ends of the rivets. While pressure is being applied, welding current is turned on and the rivet is united with the bared end of the cable by projection welding by virtue of the sharp corner or edges 38, which engage one of the electrodes, melt. The melted metal flows over the strands and excess metal flows into the bottom of the recess, or, if a single wire, or conductor, is used the melted metal will surround the conductor.

The securing and deforming of all terminals carried by the closure may be attained either simultaneously with a deforming tool having the necessary recesses 33 or may be attained progressively by a single die. Also the welding of all of the lead wires may be fused to their respective terminals either simultaneously or may be attained separately.

In order to facilitate the securing of the hared areas of a plurality of cables 40 at the same time to their respective rivets the notches, formed in the tips or ends of the terminal rivets, should be arranged at ditferent angles with respect to each other as shown in Fig. 4. By that arrangement the cables may be nested in the manner similar to that shown in Fig. 5.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to he, understood that other forms might be adopted.

What is claimed is as follows:

In a method of making an electrical connection, the steps comprising; providing an insulating support having a plurality of openings therein, forcing a terminal having an annular shoulder portion adjacent to one end and an intermediate shoulder thereon into each of said open-v ings from one side of the support, each of said terminals being formed of a ductile metal, deforming the terminal on the other side of said support opposite the end shoulder portion using a tool having a lower end formed with a series of depending swaging lugs operable to deform the intermediate shoulder of the terminal to form a plurality of extensions extending, from the terminal securing the terminal to saidsupport, notching the free end of the terminal on the side of the extensions simultaneously with the deforming step using said References Cited in the file of this patent UNITED STATES PATENTS 774,810 Willis Nov. 15, 1904 868,067 Berry Oct. 15, 1907 1,685,382 Stuart Sept. 25, 1928 1,939,105 Christy Dec. 12, 1933 2,127,050 Smith Aug. 16, 1938 2,336,556 Malloy Dec. 14, 1943 2,414,604 Newcombe Jan. 21, 1947 2,422,380 Whitaker June 17, 1947 2,436,019 Rosendale -..Feb. 17, 1948 2,464,405 Knauf Mar. 15, 1949 2,504,777 Wreford Apr. 18, 1950 2,533,987 Bahr Dec. 12, 1950 FOREIGN PATENTS 277,414 Germany Dec. 8, 1912 347,635 Great Britain Apr. 29, 1931 366,144 Great Britain Feb. 1, 1932 597,773 Germany May 30, 1934 

